The optical compact disc (CD) is universally recognized as a superb medium for storage of digital data. Its high packing density, low manufacturing cost and relative immunity to mishandling are unmatched by other media. The success of the CD as a carrier of high fidelity audio is likely to be repeated in the realm of Multimedia, where the technology has been adapted to the broader task of storing digitized audio, video and alphanumeric information for a variety of purposes, conforming to a plethora of standards such as DVD, CD-ROM, CD-Video, CD-I, etc.
To date, CD ROM software copyright owners have not had to contend with the rampant piracy (unauthorized copying) that afflicts the videocassette and audiocassette media. This is almost entirely due to the large capital investment costs associated with mastering and replicating CDs, which creates substantial financial barriers to piracy. However, compact disc recording machines capable of making perfect copies of data from pre-recorded CDs are now available for professional users for about two thousand dollars and it is very likely that a few years from now, consumer affordable player-recorders will be widely available. This will create a serious conflict between software producers' needs to sell their product for $50+ to make a profit, and the consumers' resulting ability to make a perfect copy for the price of a blank disc, projected to be in the $10 to $20 range soon. The problem is likely to be much more severe than the piracy afflicting the video business, because, while few people want to watch a movie more than once, many Multimedia software products are intended to be used repeatedly, so that ownership rather than rental is likely to be the norm.
The fundamental problem solved by this invention is to ensure that consumers can only enjoy a software manufacturer's products by playing legitimately manufactured CDs.
One approach to his piracy problem would be the inclusion of special anti-copy circuitry within CD-recorders, mandated by general agreement between the manufacturers, similar to the Serial Copy Management System (SCMS) developed for the Digital Audio Tape (DAT) medium. With this scheme the CD-recorder would look for a special copy-prohibit instruction in the digital data and on finding it, would stop recording. However, such a system offers very limited protection. Even when the SCMS system was first proposed for the DAT medium, it was fully appreciated that it presented little protection from professional or even amateur pirates, who, knowing the data format, could, and subsequently did, build inexpensive "black boxes" (electronic circuits) to remove the copy-prohibit instruction thereby enabling the recorders to make unlimited copies.
The applicants believe that all anti-copy systems relying on copy-prohibit instructions inserted in the data stream can be defeated by black boxes of the same order of complexity and cost at that of the circuitry within the CD-recorder that looks for these instructions. Such systems are therefore of limited effectiveness. The black box would be connected in line between a CD-player and a CD-recorder and would look for the special copy-prohibit instructions in the data stream and simply remove or modify these instructions. It is to be expected, therefore, that if this kind of anti-copy system were adopted, inexpensive black boxes would proliferate.
A further difficulty with this approach to copy protection is the need to ensure that all CD-recorder manufacturers include the necessary detection circuitry in their products. Some manufacturers may not comply, perhaps in the expectation of increasing their market share. The presence of even a small percentage of non-complying machines in the marketplace could jeopardize the viability of this type of copy-protection scheme.
For the foregoing reasons, there is a need for a copy-protection system for the compact disc medium that provides a high level of protection to software rights owners, that is immune to black boxes and that is not compromised by the refusal of a few hardware manufacturers to comply with the standard.